The present invention relates, in general, to the field of electric machines, and more particularly to improvements in laminations for use in electric motors and/or other static or dynamic electric machines. The invention also relates to a method of making such laminations.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
In order to dissipate heat produced during operation of a motor, stacks of laminations, also called electrical steel sheets, are used, whereby laminations with spacing strips are arranged at defined intervals with respect to one another between laminations without spacing strips to thereby provide radial ventilation. The spacing strips are used to maintain a specific distance between a lamination with the spacing strips and a neighboring lamination. As a result, free spaces are created between the laminations to allow air to flow and thereby cool the motor.
Heretofore, a lamination with spacing strips has been manufactured by initially stamping the outer boundary and the inner boundary of the lamination out of a metal sheet, or burning out the outer boundary and the inner boundary by means of a focused laser beam. Then, the spacing strips, which have previously been stamped out of a metal sheet in a separate process, are fitted at right angles on the lamination, using spot-welding. This manufacturing process is relatively time-consuming and cost-intensive. Furthermore, welding of spacing strips to a lamination often leads to inadequate attachment of the spacing strips so that the lamination is less capable of resisting the pressure exerted on it. In other words, if the pressure is too high, the spacing strips will break off the lamination.
It would therefore be desirable and advantageous to provide an improved lamination which obviated prior art shortcomings and which is easy and relatively inexpensive to manufacture.